Problem with this is that we already know people are making multiple accounts to downvote, seeing as a good number are brand new accounts are there just to give the game a 0 and there are even signs of bots being used. So simple moderation isn't really viable. What they'll do is just delete all the0 scores for a few days then call it a day. The ultimate response would be for people to realise that user scores are utterly worthless and aren't worth putting any stock into.
That's not true though.
Browse some other games on metacritic for reference.
That Pokemon DLC has 71 critic score and 6.8 user score.
The recent Xenoblade remake is 89 from critics and 9.2 from users.
Those are just random checks.
Oftentimes users will downvote a game with performance issues far more harshly than reviewers who seem quite forgiving in that aspect.
So the user scores can be useful.
This "waaaah review bombing" thing only seems to come around when different agendas clash and suddenly the critics are seen as infallible commentators on gaming and the audience is just a bunch of bots and bigots.
Its so predictable.